The SNP hit a high point in the October 1974 general election, polling almost a third of all votes in Scotland and returning 11 MPs to Westminster. This success was not surpassed until the 2015 general election. However, the party experienced a large drop in its support at the 1979 General election, followed by a further drop at the 1983 election.

In May 2011, the SNP won an overall majority in the Scottish Parliament with 69 seats. Overall majorities are unusual in the Additional Member system that is used for elections to the Scottish Parliament, which was specially designed by the Labour UK government in 1999 to prevent any party gaining overall control of the parliament.[25]

Based on their 2011 majority, the SNP government held a referendum on Scottish independence in 2014. The "No" vote prevailed in a close-fought campaign, prompting the resignation of First Minister Alex Salmond. Forty-five percent of Scottish voters cast their ballots for independence, with the "Yes" side receiving less support than late polling predicted.[26]

The SNP rebounded from the loss in the independence referendum at the UK general election in May 2015, led by Salmond's successor as first minister, Nicola Sturgeon. The party went from holding six seats in the House of Commons to 56, mostly at the expense of the Labour Party. All but three of the fifty nine constituencies in the country elected an SNP candidate. The BBC News described the historic result as a "Scots landslide".[27]

Constitution and structure

The primary level of organisation in the SNP are the local Branches. All of the Branches within each Scottish Parliament constituency form a Constituency Association, which coordinates the work of the Branches within the constituency, coordinates the activities of the party in the constituency, and acts as a point of liaison between an MSP or MP and the party. Constituency Associations are composed of delegates from all of the Branches within the constituency.

The annual National Conference is the supreme governing body of the SNP, and is responsible for determining party policy and electing the National Executive Committee. The National Conference is composed of:

The National Council serves as the SNP’s governing body between National Conferences, and its decisions are binding, unless rescinded or modified by the National Conference. There are also regular meetings of the National Assembly, which provides a forum for detailed discussion of party policy by party members.

The SNP's leadership is vested in its National Executive Committee (NEC), which is made up of the party's elected office bearers and six elected members (voted for at conference). The SNP parliamentarians (Scottish, Westminster and European) and councillors have representation on the NEC, as do the Trade Union Group, the youth wing and the student wing.

Membership

Since 18 September 2014 (the day of the Scottish independence referendum) party membership has more than quadrupled (from 25,642), surpassing the Liberal Democrats to become the third largest political party in the United Kingdom in terms of membership.[28] As of March 2015, the Party had well exceeded the 100,000 membership mark.[29]

According to accounts filed with the Electoral Commission for the year ending 2012, the party had a total income of £2,300,459 and a total expenditure of about £2,656,059.[30]

The Scottish National Party did not have a clear ideological position until the 1970s, when it sought to explicitly present itself as a social democratic party in terms of party policy and publicity.[33][34] During the period from its foundation until the 1960s, the SNP was essentially a moderate centrist party.[33] Debate within the party focused more on the SNP being distinct as an all-Scotland national movement, with it being neither of the left or the right, but constituting a new politics that sought to put Scotland first.[34][35]

The SNP was formed through the merger of the centre-left National Party of Scotland (NPS) and the centre-right Scottish Party.[34] The SNP’s founders were united over self-determination in principle, though not its exact nature, or the best strategic means to achieve self-government. From the mid-1940s onwards, SNP policy was radical and redistributionist in relation to land and in favour of ‘the diffusion of economic power’, including the decentralization of industries such as coal to include the involvement of local authorities and regional planning bodies to control industrial structure and development.[33] Party policies supported the economic and social policy status quo of the post-war welfare state.[33][36]

By the 1960s, the SNP was starting to become defined ideologically, with a social democratic tradition emerging as the party grew in urban, industrial Scotland, and its membership experienced an influx of social democrats from the Labour Party, the trade unions and the Campaign for Nuclear Disarmament.[35][37] The emergence of Billy Wolfe as a leading figure in the SNP also contributed to this movement to the left. By this period, the Labour Party were also the dominant party in Scotland, in terms of electoral support and representation. Targeting Labour through emphasising left-of-centre policies and values was therefore electorally logical for the SNP, as well as tying in with the ideological preferences of many new party members.[37] In 1961 the SNP conference expressed the party’s opposition to the siting of the USPolaris submarine base at the Holy Loch. This policy was followed in 1963 by a motion opposed to nuclear weapons: a policy that has remained in place ever since.[37] The 1964 policy document, SNP & You, contained a clear centre-left policy platform, including commitments to full employment, government intervention in fuel, power and transport, a state bank to guide economic development, encouragement of cooperatives and credit unions, extensive building of council houses by central and local government, pensions adjusted to cost of living, a minimum wage and an improved national health service.[33]

The ’60s also saw the beginnings of the SNP’s efforts to establish an industrial organisation and mobilise amongst trade unionists in Scotland, with the establishment of the SNP Trade Union Group, and identifying the SNP with industrial campaigns, such as the Upper-Clyde Shipbuilders Work-in and the attempt of the workers at the Scottish Daily Express to run as a cooperative.[33] For the party manifestos for the two 1974 general elections, the SNP finally self-identified as a social democratic party, and proposed a range of social democratic policies.[35][36] There was also an unsuccessful proposal at the 1975 party conference to rename the party as the Scottish National Party (Social Democrats).[16]

There were further ideological and internal struggles after 1979 with the 79 Group attempting to move the SNP further to the left, away from being what could be described a "social-democratic" party, to an expressly "socialist" party. Members of the 79 Group – including future party leader and First MinisterAlex Salmond – were expelled from the party. This produced a response in the shape of the Campaign for Nationalism in Scotland from those who wanted the SNP to remain a "broad church", apart from arguments of left vs. right. The 1980s saw the SNP further define itself as a party of the political left, such as campaigning against the poll tax.[33]

Ideological tensions inside the SNP are further complicated by arguments between the so-called SNP gradualists and SNP fundamentalists. In essence, gradualists seek to advance Scotland to independence through further devolution, in a "step-by-step" strategy. They tend to be in the moderate left grouping, though much of the 79 Group was gradualist in approach. However, this 79 Group gradualism was as much a reaction against the fundamentalists of the day, many of whom believed the SNP should not take a clear left or right position.[33] In its economic and welfare state policies, the party has in recent years adopted a markedly feminist profile, influenced by thinkers such as Ailsa McKay.[38]